JP2009000293A - Dual energy system and its image collection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dual energy system and its image collection method for collecting images different in energy at the highest driving rate of a planar detector by making a period that an X-ray cannot be radiated shorter than a period that an X-ray of the planar detector cannot be radiated. <P>SOLUTION: An X-ray diagnostic treatment device 10 comprises an X-ray tube 22, an X-ray generation part having a filter part 23, an X-ray detection part 12 having the planar detector 32, and a system control unit 15. The filter part 23 comprises a plurality of filters having different X-ray absorption characteristics. The plurality of filters are switched by the system control unit 15 and by this switch, images of different line qualities are continuously collected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dual energy system that collects an image for dual energy subtraction by switching filters using an X-ray flat panel detector and an image collecting method thereof.

  In conventional X-ray photography, a dual energy system using CR is often used. In this case, a filter that absorbs X-ray energy is sandwiched between two CRs, and two images with different energies are collected by one imaging (see, for example, Patent Documents 1 and 2 below).

On the other hand, an attempt has been made to realize a dual energy system using a flat detector (for example, see Patent Document 3 below). However, because of the structure of the flat detector, it is difficult to collect images by superimposing two flat detectors. For this reason, since two images with different energies cannot be collected by one X-ray irradiation, it is necessary to collect images having different energies by two X-ray irradiations.
Japanese Patent No. 2874317 JP-A-3-106343 US Pat. No. 6,683,934

  By the way, when a flat panel detector is used, it is possible to collect moving images such as 30 fps, and if the filter can be switched at high speed, even a flat panel detector can collect an image with little motion blur.

  On the other hand, when the filter is switched, there is a period in which the boundary of the filter enters the X-ray irradiation region and the X-ray cannot be irradiated. Therefore, when the filter is switched at high speed, it is necessary to shorten the time during which the X-rays cannot be irradiated.

  Further, when X-rays are irradiated in a pulsed manner, X-rays cannot be irradiated while the flat detector is reading a signal. That is, if the filter cannot be switched during this readout period, images with different energies cannot be collected at the highest driving rate of the flat panel detector.

  In addition, in order to keep collecting images with different energies alternately at high speed, taking advantage of the characteristics of the flat panel detector, multiple filters are evenly arranged on the disk and kept rotating at a constant speed. Can continue to collect.

  However, as described above, when a plurality of filters are switched, a boundary between the filters enters the X-ray irradiation region, so that a period during which X-rays cannot be irradiated occurs. If the period during which X-rays cannot be irradiated is shorter than the period during which X-rays from the flat detector cannot be irradiated, images with different energies can be collected at the highest driving rate of the flat detector.

  Therefore, it is necessary to design so that the size of the filter and the size of the X-ray irradiation region maintain a certain relationship.

  Therefore, the present invention has been made in view of the above circumstances, and its purpose is to shorten the period during which X-rays cannot be irradiated to be shorter than the period during which X-rays from the flat detector cannot be irradiated. To provide a dual energy system capable of collecting images having different energies at a driving rate and an image collecting method thereof.

  That is, the present invention includes an X-ray generator, a flat panel detector for collecting X-ray images, a plurality of filters having different X-ray absorption characteristics, and a switching device that switches the filters, and is continuously different. In a dual energy system that collects images of radiation quality, the switching device switches the plurality of filters from the start of data reading of the flat panel detector to the start of the next X-ray irradiation.

  In addition, the present invention provides an X-ray generation unit capable of irradiating a subject with X-rays having different energy, a plurality of filters having absorption characteristics of the X-rays having different energy irradiated from the X-ray generation unit, Control means for switching a plurality of filters, a flat detector for collecting X-ray images by detecting X-rays transmitted through the plurality of filters and the subject and irradiated by the X-ray generation means, and the plane An X-ray image data collected by the detector, and collecting means for continuously collecting images of different line qualities, the control means from the start of reading the image data of the flat detector The plurality of filters are switched before the start of the next X-ray irradiation by the X-ray generation means.

  Furthermore, the present invention provides an X-ray generator, a flat panel detector for collecting X-ray images, a plurality of filters having different X-ray absorption characteristics arranged on the same disk, and a switching device for switching the filters. In the image acquisition method of the dual energy system that continuously collects images with different radiation qualities, the switching timing of the plurality of filters is the start of the next X-ray irradiation from the start of data reading of the flat panel detector. It is characterized by being performed by.

  According to the present invention, the period during which X-rays cannot be irradiated can be made shorter than the period during which X-rays from the flat panel detector cannot be irradiated, and images with different energies can be collected at the highest driving rate of the flat panel detector. A dual energy system and its image acquisition method can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a first embodiment of the present invention and is a block diagram showing an overall configuration of an X-ray diagnostic treatment apparatus to which a dual energy system is applied.

  An X-ray diagnosis and treatment apparatus 10 according to this embodiment includes an X-ray generation unit 11, an X-ray detection unit 12, and a C-shaped C-arm in which the X-ray generation unit 11 and the X-ray detection unit 12 are arranged to face each other. And a mechanism control unit 14, a system control unit 15, an operation unit 16, an image storage circuit 17, and a display unit 18.

  The X-ray generation unit 11 includes a high voltage generation unit 21, an X-ray tube 22 and a filter unit 23. The X-ray tube 22 receives power supply from the high voltage generator 21 and radiates X-rays toward a flat detector 32 described later in the X-ray detector 12. The high voltage generator 21 is configured such that the tube voltage and the filament current are arbitrarily adjusted by the system controller 15. The system control unit 15 controls the entire control operation of the X-ray diagnostic treatment apparatus 10. The system control unit 15 also controls the flat panel detector 32 in synchronization with the X-ray generation control by the X-ray tube 22.

  On the other hand, the X-ray detection unit 12 includes a gate driver 31, a flat panel detector 32, an image data generation unit 38 including a charge / voltage converter 34, an A / D converter 35, and a parallel / serial converter 36. It is configured. The flat detector 32 detects X-rays incident through the subject P from the X-ray tube 22 described above under the control of the system control 15 via the gate driver 31. Then, an electric signal corresponding to the detected X-ray intensity is output to the charge / voltage converter 34 in the image data generation unit 38. The output converted by the charge / voltage converter 34 is supplied (collected) as image data to the image storage circuit 17 via the A / D converter 35 and the parallel / serial converter 36.

  The image data stored in the image storage circuit 17 is subjected to image processing via the display image memory 41, the D / A converter 42, and the display circuit 43 in the display unit 18, and is displayed on the monitor 44 as an image. . The operator can perform X-ray diagnostic treatment by operating the operation unit 16 while confirming the image displayed on the monitor 44.

  The holding unit 16 is driven to rotate by the system control unit 15 and the mechanism control unit 14. At this time, the X-ray generation unit 11 and the X-ray detection unit 12 rotate around the same rotation axis.

  As shown in FIG. 2, the filter unit 23 includes, for example, a filter 24 that is formed in a disk shape and can rotate in a predetermined direction for collecting images of two types of energy, high energy and low energy. And a filter switching device 25 for switching the filter 24. The filter switching device 25 switches the filter 24 at a timing that will be described in detail later under the control of the system control unit 15. The X-rays emitted from the X-ray tube 22 a in the X-ray tube 22 are detected by the flat detector 32 as two types of energy, high and low, by the filter 24 switched by the filter switching device 25. It has become.

  In the X-ray diagnosis and treatment apparatus 10 having such a configuration, an imaging start operation by a switch (not shown) of the operation unit 16 is performed by an operator. Then, the operation signal from the operation unit 16 is processed by the system control unit 15, and the movement amount of the holding unit 13 and a bed (not shown) is controlled via the mechanism control unit 14. Further, the high voltage generation unit 21 is controlled, and X-rays start to be emitted from the X-ray tube 22 through the filter unit 23.

  The X-rays irradiated here pass through the subject P placed on a bed (not shown), and the transmitted X-rays are incident on the flat detector 32 in the X-ray detector 12. The transmitted X-rays incident on the flat detector 32 are converted into digital signals by the charge / voltage converter 34, the A / D converter 35 and the parallel / serial converter 36 in synchronization with the X-ray irradiation by the system controller 15. After being converted into data, it is temporarily stored in the image storage circuit 17 as image data. The stored image is displayed on the monitor 44 via the display image memory 41, the D / A converter 42, and the display circuit 43.

  Here, switching of the filter 24 described above will be described.

  As in the present embodiment, when a flat detector 32 is used and images of different energies are collected by time division by switching the filter 24 and energy subtraction is performed, as described above, there is a period during which X-rays cannot be irradiated without fail. Exists. In order to switch between the two types of filters at a high speed depending on a period during which the boundary of the filter 24 is in the X-ray irradiation region (an impossible period described later), it is important to minimize the impossible period. . That is, it is necessary to synchronize with the switching timing of the filter 24 and the driving timing of the flat detector 32.

  FIG. 3 is a timing chart for explaining the X-ray irradiation timing of the filter 24 and the reading timing of the flat panel detector (FPD) 32. In the figure, it is assumed that the filter A absorbs high energy and the filter B absorbs lower energy than the filter A.

  FIG. 4 is a diagram for explaining a possible period and an impossible period of X-ray irradiation.

  Here, the possible period is a period during which the X-rays irradiated by the filters can be uniformly absorbed. On the other hand, the impossible period (denoted as impossible in FIG. 3) is a period during which X-rays cannot be absorbed uniformly. The period during which X-rays cannot be absorbed uniformly refers to a period in which filter boundaries and the like enter the X-ray irradiation area, and there are a plurality of filters throughout the irradiation area, resulting in non-uniform filter characteristics. It is.

  During the reading period of the FPD 32, the next X-ray cannot be irradiated. Therefore, the X-ray irradiation interval can be minimized by making the X-ray irradiation impossible period associated with the switching of the filter 24 included in the readout period of the FPD 32. In this case, the next X-ray may be irradiated simultaneously with the end of reading of the FPD 32.

  For example, in FIG. 4, it is assumed that the filter 50 includes two types of filters A 50 a and B 50 b that absorb energy of high and low. Here, assuming that the filter 50 rotates clockwise, two states shown on the left side of FIG. 4, that is, a period in which the X-ray irradiation region 26 exists only in the filter A 50 a is a possible period (T 1 ) In the two states shown on the right side, the X-ray irradiation region 26 includes not only the filter A50a but also a part other than the filter A50a (for example, on the boundary between the filter A50a and the filter B50b, in the filter B50b). This is a period (T2) during which the filter A 50a cannot perform X-ray irradiation.

  Since the filter may always move, the period from the start to the end of the filter switching operation is not a possible period. Even if the filter moves during X-ray irradiation, there is no problem as long as the filter characteristics in the irradiation region are uniform. Furthermore, even if the filter switching operation is started simultaneously with the X-ray irradiation, there is no problem as long as the filter characteristics do not change during the X-ray irradiation period.

  Next, the filter switching operation in this embodiment will be described with reference to the flowchart of FIG. This switching operation is mainly performed by the system control unit 15. Explanation of the overall operation of the X-ray diagnostic treatment apparatus 10 is omitted.

  When this routine is entered, first, at step S1, it is determined whether or not to change the collection mode. Here, if there is dual energy, the process proceeds to step S2 and the rotation operation of the filter 24 is started. Alternatively, the operation cycle of the filter 24 is changed. If the operation cycle of the filter 24 becomes stable in step S3, X-ray acquisition is possible.

  Next, in step S4, the operator presses a fluoroscopy or photographing button (not shown) of the operation unit 16. Then, in step S5, X-rays are emitted from the X-ray tube 22 in synchronization with the position information of the filter 24 as shown in the timing chart of FIG. Thereafter, in step S <b> 6, a differential image of images collected using different filters, for example, the filters A <b> 50 a and B <b> 50 b, is output to the image storage circuit 17.

  In step S7, the state of the fluoroscopy or the photographing button (not shown) of the operation unit 16 is determined. If the button is pressed (ON), the process proceeds to step S5. If the button is not pressed (OFF), the process proceeds to step S8. In step S8, it is determined whether or not the collection mode is switched. As a result, when there is no switching, the process proceeds to step S4, and when there is switching, the process proceeds to step S1.

  On the other hand, if the acquisition mode is not switched in step S1, that is, if there is no dual energy, the process proceeds to step S9 and the filter 24 is stopped at the standard position for performing desired energy collection. Next, when the operator presses a fluoroscopy or imaging button (not shown) of the operation unit 16 in step S10, X-rays are emitted from the X-ray tube 22 in accordance with a predetermined setting period in step S11. Thereafter, the collected image is output to the image storage circuit 17 in step S12.

  In step S13, the state of the fluoroscopy or the photographing button (not shown) of the operation unit 16 is determined. If the button is pressed (ON), the process proceeds to step S13. If the button is not pressed (OFF), the process proceeds to step S14. In step S14, it is determined whether or not the collection mode is switched. As a result, when there is no switching, the process proceeds to step S10, and when there is a switching, the process proceeds to step S1.

  In the above-described example, the filter is described as being formed in a disk shape and rotating, but the present invention is not limited to this.

  For example, as shown in FIG. 6, a rectangular filter 52 may be used to reciprocate. In this case, it is assumed that the filter 52 including the filter A 52a and the filter 52b reciprocates in the left-right direction in FIG. Even in such a case, there is a possible period T1 in which X-ray irradiation is possible and an impossible period T2 in which X-ray irradiation is not possible, as in the case of the disk-shaped filter.

  FIG. 7 and FIG. 8 are diagrams showing X-ray irradiation impossibility periods in a disk-shaped filter rotating in a predetermined direction and a rectangular filter reciprocating in a predetermined direction, respectively.

  As can be seen from FIG. 7 and FIG. 8, the period from one boundary to the other boundary of the filters having different energy absorption is the period during which X-ray irradiation is impossible.

  By the way, when a plurality of filters are arranged on a disk, and each time X-ray irradiation is performed repeatedly to stop the filter by moving the stopped filter to switch the filter, it takes time. It is conceivable that a deviation occurs in the angle at rest. When the filter is rotated in synchronization with the irradiation timing pulse, it is desirable to use a synchronous motor or the like. However, if the filter is continuously rotated, an error occurs.

  When energy subtraction is performed by continuously rotating a disk-shaped filter, if an X-ray irradiation region has a boundary, X-ray irradiation cannot be performed as described above. That is, sufficient X-ray irradiation time cannot be ensured without considering the size of the X-ray irradiation region and the filter size.

  When the collection rate is slow, it is not necessary to rotate the disk-shaped filter continuously. This is because there is no need to rotate the filter if the filter of the X-ray irradiation region can be switched during the period from the start of reading of the flat panel detector to the irradiation of the next X-ray.

  Therefore, in order to stably operate the filter before X-ray irradiation, in the case of circular motion or rotational motion, if the rotational motion is always performed at a constant speed, images can be easily collected at a constant cycle.

  Normally, when pulse fluoroscopy or sequence imaging is performed, a mode including information such as a collection rate is selected before the irradiation button is pressed. Therefore, the rotational motion is started simultaneously with the mode switching. By doing in this way, rotation can be stabilized before X-ray irradiation.

  Further, instead of rotating the filter in accordance with the X-ray irradiation timing, for example, the rotation position is confirmed by a laser or the like, and X-rays are irradiated in synchronization with the position information of the filter. In an energy subtraction device that switches filters by rotational movement, the effects of rotational errors can be eliminated by controlling the X-ray irradiation and the driving timing of the flat panel detector based on the angle information of the rotation of the filter. it can.

  As described above, even when there is an X-ray irradiation disabled period associated with the filter switching, it is possible to collect images according to the FPD drive rate without being affected by the period. Further, by performing filter switching at this timing, it is possible to collect at the maximum driving speed of the FPD.

  Incidentally, as described above, in the case of a filter intended to absorb different types of energy, the filter basically rotates at 1 / n of the collection period. That is, as shown in FIGS. 9A and 9B, in the case of two types of energy, the period is 1/2. When n types of filters are evenly arranged on the disk-shaped filter 50, the filter 50 is rotated at a period of 1 / n of the collection period. The rotation position is detected by grasping the angle information through the position detection hole 55 formed on the filter 50.

  If the pulse of the system control unit 15 is to be used as a master, the rotational position detection described above is compared with the deviation of the pulse of the system control unit 15, and if the predetermined allowable range is exceeded, the control to increase or decrease the rotation angle is performed. It is also possible to perform control such that the positional relationship of the system pulse and the positional relationship is matched.

  Thereby, it is possible to alternately collect images having different energies continuously without being affected by the initial value or error of the rotating filter.

  FIG. 10 is a diagram showing an arrangement example of the X-ray irradiation region.

  The above-described position detection hole 55 by a laser or the like is disposed inside or outside a region including the irradiation region. FIG. 10 shows an example in which the position detection hole 55 is arranged inside the region including the X-ray irradiation region 26.

  Also, it is a disk-shaped filter, and n types of filters are equally arranged. When images are collected continuously m times by each filter, the filters are rotated at a cycle of (nXm) of the collection rate. To.

  FIG. 11 shows a disk-like filter 50 in the case of n = 2 and m = 4, and the filter 50 is rotated at a period of 1/8 of the collection rate. In this way, by continuously collecting m = 4 images of the same filter, m images can be averaged and an image with reduced noise can be created. Subtraction can be performed between different images.

  In the case of the example in FIG. 11, the filter type changes from A → A → A → A → B → B → B → B. On the other hand, when the two types of filters are switched, A → B → A → B → A → B → A → B.

  In order to obtain the averaging, there is a method as described above, but a filter in which two types of filters are equally arranged is rotated at a period of one half of the collection rate, and the two types of energy are different. Images may be collected alternately, and images collected by the same filter may be converted after collection.

  Next, the arrangement of the X-ray irradiation area in the case of a disk-like filter will be described.

As shown in FIG. 12, in the disk-shaped filter 56 _1, X-ray irradiation area 26, the border 56 ₁₁ and 56 with the _12, and the position detecting hole 58 ₁ from outside the area lines 57 ₁ It is arranged on the outer side. In this case, the angle .theta.2 ₁ occupied by the filter 56 ₁ to the in the X-ray irradiation area 26 to rotate is increased and with respect to the filter 56 ₁ of occupied angle .theta.1, irradiation period T1 ₁ is shortened.

On the other hand, as shown in FIG. 13, it is at the disk-shaped filter 56 _2, X-ray irradiation area 26 is outside the region between, and from the position detecting hole 58 ₂ of the boundary 56 ₂₁ and 56 ₂₂ It is arranged outside the line 57 _2. In this case, the angle θ2 ₂ occupied by the X-ray irradiation region 26 in the rotating filter 56 ₂ is larger than the angle θ1 occupied by the filter 56 ₂ , and the irradiation possible period T1 ₂ is the above-described irradiation possible period T1. Longer than _one .

The filter 56 ₁ and X-ray irradiated area 26 on the filter 56 ₂ shown in FIG. 13 shown in FIG. 12, the same size (the same area). That is, the filter 56 ₁ and the filter 56 ₂ becomes a shape similar, the size of the area lines 57 ₁ and area line 57 ₂ are different. From the ratio of the X-ray irradiation period in one cycle of X-ray acquisition, the relationship between the size of the X-ray irradiation region and the rotation radius is determined.

  This will be described with reference to FIG.

In the disk-shaped filter 56, the angle occupied by the filter 56 ₁ (A) is represented by θ1, and the angle occupied by the irradiation region in the filter 56 is represented by θ2.

Referring to the timing chart of FIG. 15, τ after the X-ray irradiation timing is the time from the start of reading the FPD to the start of the next X-ray irradiation, assuming T = 1 period. Then, the following relational expression is established from the θ1 and θ2.
θ2 / θ1 ≦ τ / T
That is, if the X-ray irradiation region is made as small as possible, the X-ray irradiation time in one cycle can be extended. In addition, the size of the disk-shaped filter 56 can be reduced. For this reason, it is better to bring the filter position closer to the X-ray tube.

  Next, a case where n types of filters are evenly arranged on a disk and images are continuously collected m times by each filter will be described with reference to timing charts of FIGS. 16 and 17.

Now, in the disk-shaped filter 58, the ratio of the rotation angle occupied by the X-ray irradiation region 26 to 1 / m of the angle occupied by one type of filter is FPD data reading at the collection period = T. Assuming the time τ from the start to the next start of X-ray irradiation, the following equation is obtained.
θ2 / (θ1 / m) ≦ τ / T
Next, a case where there are a plurality of collection rates and X-ray irradiation times are different will be described with reference to the timing chart of FIG.

Now, as shown in FIG. 18, a case where there are two collection rates will be described. In this case, taking X-ray irradiation timing 1 as an example, one cycle = T1, and the maximum irradiation time is τ1. Similarly, in the case of X-ray irradiation timing 2, it is assumed that 1 period = T2, and the maximum irradiation time is τ2. Here, based on the case where the ratio of the maximum irradiation time to one cycle is maximum (in this example, X-ray irradiation timing 2), the filter size is set so that the relationship between the filter and the X-ray irradiation region satisfies the following equation. It is determined.
τ2 / T2> τ1 / T1
Therefore,
(Θ1-θ2) / θ1> τ2 / T2
In this manner, the filters are sequentially switched while rotating the rotating filter at a constant speed, and a sufficient X-ray irradiation time can be secured in each filter.

(Second Embodiment)
Next, a second embodiment of the present invention will be described.

  In the first embodiment described above, the filter for collecting two types of energy images of the two types of filters, high energy and low energy, has been described. In the second embodiment, an example in which three types of filters are arranged will be described as an example in which more types of filters are arranged.

  In the second embodiment, the basic configuration and operation of the X-ray diagnostic treatment apparatus are the same as those in the first embodiment described above. Are denoted by the same reference numerals, illustration and description thereof are omitted, and only different portions will be described.

  FIGS. 19A to 19C are diagrams showing an example in which three types of filters having different energies are evenly arranged on a disk. In the figure, the disc-shaped filter 60 is composed of three types of filters having different energies, for example, a filter A (green) 60a, a filter B (blue) 60b, and a filter C (red) 60c. FIG. 19A shows a state where the X-ray irradiation region 26 exists in the filter A 60a. Similarly, FIG. 19B shows a state in which the X-ray irradiation region 26 exists in the filter B60b, and FIG. 19C shows a state in which the X-ray irradiation region 26 exists in the filter C60c. .

  When the filter 60 is rotated in the direction as shown in FIG. 19A, the three filters 60a, 60b, and 60c are switched in order as in A → B → C → A →. The filter 60 may be rotated at a period of 1/3 of the collection rate.

  Further, when it is desired to alternately collect images using only two types by using this filter 60, it is preferable to rotate the image at a cycle of a half of the collection rate.

  As described above, in this filter 60, the three types of filters 60a, 60b, and 60c are evenly arranged, so that one type of filter is equally divided by 120 degrees. Here, if only two types of filters are used, only 60 degrees, which is half of 120 degrees, is used for each type of filter.

  For example, FIG. 20 is a diagram showing an example in which filters are used in the order of B → C → B → C →... In the filter 60 composed of three types of filters 60a, 60b, and 60c. First, as shown in FIG. 20A, it is assumed that the X-ray irradiation region 26 exists in the filter B 60b. Next, when the filter 60 rotates 180 degrees from this state, as shown in FIG. 20B, the X-ray irradiation region 26 is on the filter C60c.

  Note that the rotation direction of the filter 60 may be either clockwise or counterclockwise because it rotates by 180 degrees.

  FIG. 21 is a diagram showing an example in which filters are used in the order of A → C → A → C →... In the filter 60 composed of three types of filters 60a, 60b, and 60c. First, as shown in FIG. 21A, it is assumed that the X-ray irradiation region 26 exists in the filter A 60a. Next, when the filter 60 rotates 180 degrees from this state, as shown in FIG. 21B, the X-ray irradiation region 26 is on the filter C60c.

  FIG. 22 is a diagram showing an example in which filters are used in the order of A → B → A → B →... In the filter 60 composed of three types of filters 60a, 60b, and 60c. First, as shown in FIG. 22A, it is assumed that the X-ray irradiation region 26 exists in the filter A 60a. Next, when the filter 60 is rotated 180 degrees from this state, as shown in FIG. 22B, the X-ray irradiation region 26 is on the filter B 60b.

  If it does in this way, the image of arbitrary two types of filters can be collected alternately using one rotating filter.

  As described above, according to the second embodiment, it is possible to switch between three filters and any two filters by using a three-fold rotating filter.

  Next, with reference to the timing chart of FIG. 23, the readout timing and X-ray irradiation timing of the flat panel detector (FPD) 32 in the second embodiment will be described.

  As shown in FIG. 23, the flat detector 32 requires a predetermined readout time. Then, the maximum X-ray irradiation time to be irradiated per time is determined depending on the region to be imaged. Therefore, the rotation period of the filter 60 is determined on the basis of this collection rate, with a period obtained by combining the maximum X-ray irradiation time and the readout time of the flat panel detector as one period.

  As a result, the time between two images can be minimized, and motion blur can be reduced.

  In the first and second embodiments described above, the disk-shaped filter and the reciprocating filter have been described. However, the present invention is not limited to this. For example, a belt-like filter may be used as long as it moves continuously. Even those configured as described above can be applied.

  The present invention is a dual energy system using a flat detector, but is not limited to a flat detector. For example, CR can also be applied in the case where it is obtained by dividing instead of simultaneously.

  Although the embodiments of the present invention have been described above, the present invention can be variously modified without departing from the gist of the present invention other than the above-described embodiments.

  Further, the above-described embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be extracted as an invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating an overall configuration of an X-ray diagnostic treatment apparatus to which a dual energy system using a flat panel detector is applied according to a first embodiment of the present invention. It is the figure which showed the basic composition of the filter part 23 of FIG. 6 is a timing chart for explaining the X-ray irradiation timing of the filter 24 and the readout timing of the flat panel detector (FPD) 32; It is a figure for demonstrating the possible period and the impossibility period of X-ray irradiation. It is a flowchart for demonstrating the switching operation | movement of the filter in the 1st Embodiment of this invention. It is a modification of 1st Embodiment, Comprising: It is a figure explaining the example which replaced with the disk shaped filter and used the rectangular filter. It is the figure which showed the X-ray irradiation impossibility period in the disk shaped filter rotated to a predetermined direction. It is the figure which showed the X-ray irradiation impossibility period in the rectangular filter which reciprocates in a predetermined direction. It is a figure for demonstrating the collection period of a disk shaped filter. It is the figure which showed the example of arrangement | positioning of a X-ray irradiation area | region. It is a disk-shaped filter, Comprising: Two types of filters are arrange | positioned equally, It is the figure which showed the example of arrangement | positioning in case an image is collected 4 times continuously by each filter. It is a diagram for explaining the arrangement of in X-ray irradiated area in the case of a disc-shaped filter 56 _1. It is a diagram for explaining the arrangement of in X-ray irradiated area in the case of a disc-shaped filter 56 _2. It is a figure for demonstrating the relationship between the size of a X-ray irradiation area | region, and a rotation radius. It is a flowchart for demonstrating the relationship between the size of a X-ray irradiation area | region, and a rotation radius. It is a figure for demonstrating the example which n types of filters are arrange | positioned equally on a disk, and collects the image of continuous m times in each filter. It is a timing chart for demonstrating the case where n types of filters are equally arrange | positioned on a disc, and the image is collected continuously m times with each filter. It is a timing chart for demonstrating the X-ray irradiation timing of a disk shaped filter in case there exist two collection rates. An example in which three types of filters having different energies are uniformly arranged on a disk is shown, (a) is a diagram showing a state in which an X-ray irradiation region 26 exists in a green filter 60a, (b) ) Is a diagram illustrating a state in which the X-ray irradiation region 26 is present in the blue filter 60b, and (c) is a diagram illustrating a state in which the X-ray irradiation region 26 is present in the red filter 60c. It is the figure which showed the example which used the filter in order of B-> C-> B-> C-> ... in the filter 60 comprised by three types of filters 60a, 60b, 60c. It is the figure which showed the example which used the filter in order of A-> C-> A-> C-> ... in the filter 60 comprised by three types of filters 60a, 60b, 60c. It is the figure which showed the example which used the filter in order of A-> B-> A-> B-> ... in the filter 60 comprised by three types of filters 60a, 60b, 60c. It is a timing chart for demonstrating the read-out timing of the flat panel detector (FPD) 32 in the 2nd Embodiment of this invention, and the irradiation timing of X-ray | X_line.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... X-ray diagnostic treatment apparatus, 11 ... X-ray generation part, 12 ... X-ray detection part, 13 ... Holding part, 14 ... Mechanism control part, 15 ... System control part, 16 ... Operation part, 17 ... Image storage circuit, DESCRIPTION OF SYMBOLS 18 ... Display part, 21 ... High voltage generation part, 22 ... X-ray tube, 23 ... Filter part, 24 ... Filter, 25 ... Filter switching apparatus, 26 ... X-ray irradiation area | region, 31 ... Gate driver, 32 ... Planar detector (FPD) 34... Charge / voltage converter 35. A / D converter 36. Parallel / serial converter 38. Image data generating unit 41. Display image memory 42. D / A converter 43: Display circuit, 44: Monitor, 50: Filter, 50a: Filter A, 50b: Filter B

Claims (35)

An X-ray generator, a flat panel detector for collecting X-ray images, a plurality of filters having different X-ray absorption characteristics, and a switching device for switching the filters, and continuously obtaining images of different line qualities In the dual energy system to collect,
The dual energy system, wherein the switching device switches the plurality of filters from the start of data reading of the flat panel detector to the start of the next X-ray irradiation.   The dual energy system according to claim 1, wherein the plurality of filters are arranged on the same disk that is rotatable in a predetermined direction. In a dual energy system in which a plurality of different filters are arranged on the same disk and a plurality of filters can be switched by rotating the disk.
A dual energy system, wherein the disk is rotated at a constant speed.   4. The dual energy system according to claim 2, wherein the collection rate mode is set and the disk on which the filter is arranged is started to rotate at a constant speed.   When a disk on which a plurality of the filters are arranged is rotating at a constant speed, at least the X-ray irradiation by the X-ray generator and the driving timing of the flat detector are controlled based on the positional information of the filters. The dual energy system of claim 2, wherein   6. The dual energy system according to claim 5, wherein when n types of filters are evenly arranged on the disk, the disk is rotated at a period of 1 / n of a collection rate.   N types of filters are uniformly arranged on the disk, and when images are collected continuously m times with each filter, the filters are rotated at a cycle of (n × m) of the collection rate. 6. The dual energy system according to claim 5.   When n types of filters are evenly arranged on the disk, the ratio of the rotation angle occupied by the X-ray irradiation region by the X-ray irradiation to the angle occupied by one type of filter is the plane detection in the collection period. The dual energy system according to claim 2, wherein the dual energy system is set to be equal to or less than a ratio of a time from the start of data reading to the next X-ray irradiation.   When n types of filters are evenly arranged on the disk and images are collected continuously m times with each of the filters, one type of filter occupies the rotation angle occupied by the X-ray irradiation region by the X-ray irradiation. The ratio of the angle to 1 / m is set to be equal to or less than the ratio of the time from the start of data reading of the flat panel detector to the start of the next X-ray irradiation in the collection period. Dual energy system.   When there are a plurality of collection rates and the X-ray irradiation time is different from the X-ray irradiation, the time excluding the X-ray irradiation time from one cycle is maximized in accordance with the case where the ratio to one cycle is maximum. The dual energy system according to claim 2, wherein the ratio of the rotation angle occupied by the X-ray irradiation region to the angle occupied by one type of filter is set to be equal to or less than the ratio.   The three types of filters are equally arranged on the disc, and when only two arbitrary types of filters are alternately used, the disc is rotated at a period of half of the collection rate. Item 3. The dual energy system according to Item 2.   The dual energy according to claim 2, wherein a collection rate that includes a maximum irradiation time of the X-ray and a readout time of the flat panel detector is selected, and the disk is rotated according to the collection rate. system. X-ray generation means capable of irradiating the subject with X-rays having different energies;
A plurality of filters having absorption characteristics of X-rays of different energy irradiated from the X-ray generation means;
Control means for switching the plurality of filters;
A flat panel detector for collecting X-ray images by detecting X-rays transmitted from the X-ray generation means through the plurality of filters and the subject;
A collecting means for reading out image data of the X-ray image collected by the flat detector and continuously collecting images of different line qualities;
Comprising
The dual energy system characterized in that the control means switches the plurality of filters between the start of reading the image data of the flat panel detector and the start of the next X-ray irradiation by the X-ray generation means.   The dual energy system according to claim 13, wherein the plurality of filters are arranged on the same disk that is rotatable in a predetermined direction.   15. The dual energy system according to claim 14, wherein the control means rotates the disk in a predetermined direction at a constant speed to switch and control the filters having the different X-ray absorption characteristics.   15. The dual energy system according to claim 14, wherein the control means reciprocates the plurality of filters in a predetermined direction to switch and control the filters having the different X-ray absorption characteristics.   16. The dual energy system according to claim 15, wherein the control means sets at least a collection rate mode and simultaneously starts rotating the disk at a constant speed.   When the disk is rotating at a constant speed, the control means controls X-ray irradiation by the X-ray generation means and driving timing of the flat detector based on positional information of the plurality of filters. 16. The dual energy system according to claim 15, characterized in that   The dual energy according to claim 18, wherein the control means rotates the disk at a period of 1 / n of the collection rate when n types of filters are evenly arranged on the disk. system.   The control means rotates n-cycles at a cycle of (n × m) of the collection rate when n types of filters are evenly arranged on the disk and images are collected continuously m times by each filter. The dual energy system of claim 18.   The control means, when n types of filters are evenly arranged on the disk, the ratio of the rotation angle occupied by the X-ray irradiation region by the X-ray generation means to the angle occupied by one type of filter, 19. The dual energy system according to claim 18, wherein the dual energy system is set to be equal to or less than a ratio of a time from the start of reading of image data of the flat panel detector to the start of the next X-ray irradiation by the X-ray generation unit in an acquisition period.   In the control means, when n types of filters are evenly arranged on the disk and images are continuously collected m times by the respective filters, the rotation angle occupied by the X-ray irradiation area by the X-ray generation means is determined. The ratio of the angle occupied by one type of filter to 1 / m is less than the ratio of the time from the start of reading the image data of the flat panel detector to the start of the next X-ray irradiation by the X-ray generation means in the collection period. The dual energy system of claim 18, wherein:   When the control means has a plurality of collection rates and the X-ray irradiation time by the X-ray generation means is also different, the time obtained by subtracting the X-ray irradiation time from one period is a first ratio to the one period. In accordance with the maximum value, the second ratio of the rotation angle occupied by the X-ray irradiation region by the X-ray generation means to the angle occupied by one type of filter is set to be equal to or less than the first ratio. The dual energy system of claim 18.   The control means, when three types of filters are evenly arranged on the disc, and when only two arbitrary types of filters are used alternately, rotates the disc at a period of half the collection rate. The dual energy system of claim 18.   The control means selects a collection rate that includes a maximum X-ray irradiation time by the X-ray generation means and a readout time of the flat panel detector, and rotates the disk according to the collection rate. The dual energy system of claim 18. An X-ray generator, a flat panel detector for collecting X-ray images, a plurality of filters having different X-ray absorption characteristics arranged on the same disk, and a switching device for switching the filters are continuously provided. In a dual energy system image acquisition method for acquiring images of different line qualities,
The dual energy system image acquisition method, wherein the switching timing of the plurality of filters is performed from the start of data reading of the flat panel detector to the start of the next X-ray irradiation.   27. The method according to claim 26, wherein the acquisition rate mode is set and the disk on which the filter is arranged starts rotating at a constant speed.   When a disk on which a plurality of the filters are arranged is rotating at a constant speed, at least the X-ray irradiation by the X-ray generator and the driving timing of the flat detector are controlled based on the positional information of the filters. 27. A method for acquiring images of a dual energy system according to claim 26.   27. The dual energy system image acquisition according to claim 26, wherein when n types of filters are evenly arranged on the disk, the disk is rotated at a period of 1 / n of the acquisition rate. Method.   N types of filters are uniformly arranged on the disk, and when images are collected continuously m times with each filter, the filters are rotated at a cycle of (n × m) of the collection rate. 27. A method for acquiring images of a dual energy system according to claim 26.   When n types of filters are evenly arranged on the disk, the ratio of the rotation angle occupied by the X-ray irradiation region by the X-ray irradiation to the angle occupied by one type of filter is the plane detection in the collection period. 27. The method of acquiring an image of a dual energy system according to claim 26, wherein the image acquisition method is set to be equal to or less than a ratio of a time from the start of data reading to the next X-ray irradiation.   When n types of filters are evenly arranged on the disk and images are collected continuously m times with each of the filters, one type of filter occupies the rotation angle occupied by the X-ray irradiation region by the X-ray irradiation. 27. The ratio of the angle to 1 / m is set to be equal to or less than the ratio of the time from the start of data reading of the flat panel detector to the start of the next X-ray irradiation in the collection period. Image acquisition method for dual energy system.   When there are a plurality of collection rates and the X-ray irradiation time is different from the X-ray irradiation, the time excluding the X-ray irradiation time from one cycle is maximized in accordance with the case where the ratio to one cycle is maximum. 27. The image acquisition method for a dual energy system according to claim 26, wherein the ratio of the rotation angle occupied by the X-ray irradiation region to the angle occupied by one type of filter is set to be equal to or less than the ratio.   The three types of filters are equally arranged on the disc, and when only two arbitrary types of filters are alternately used, the disc is rotated at a period of half of the collection rate. Item 27. The image acquisition method of the dual energy system according to Item 26.   27. The dual energy according to claim 26, wherein a collection rate that includes the maximum irradiation time of the X-ray and the readout time of the flat panel detector is selected, and the disk is rotated according to the collection rate. System image collection method.

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